In recent years, communication systems having a plurality of user terminals connected to and capable of sharing a printer via a network have become widespread in use. With such a communication system, each user terminal can transmit print data to the printer, while the printer prints images on paper based on the data in the order received and outputs the printed material to a discharge tray of the printer. Consequently, the printer outputs the printed results (paper) based on print data received from different user terminals to the discharge tray of the printer, mixing the printed results for different users on the same discharge tray.
As a result, each user must look through the stack of paper on the discharge tray to extract the printed results outputted according to the user's command. However, when at a rush at work, a user may mistakenly take printed results outputted by another user.
When a user mistakenly takes the wrong printout from the discharge tray, the user that original issued a command to print the job cannot obtain this printed material from the discharge tray and must repeat the printing operation from the user's own terminal, resulting in a great inconvenience to the user.
U.S. Patent Application Publication No. 2004/168130A1 proposes a technology for printing a mark capable of identifying the user on the back surface of the paper. Since such a mark easily identifies the user, a different user is less likely to take the wrong printed results from the discharge tray.